Molding apparatus and molding method

ABSTRACT

A molding apparatus that adsorbs thermoplastic resin extruded in a sheet form from an extruding machine, onto a cavity of a mold, and shapes the thermoplastic resin into a shape according to the cavity is provided. The molding apparatus may include a frame that is positioned on a periphery of the mold and is movable relative to the mold, wherein a suction part for suctioning the thermoplastic resin is provided in a contact surface of the frame to contact the thermoplastic resin, and the suction part is provided in a linear shape along with a longitudinal direction of the frame positioned on the periphery of the mold.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of pending U.S. patent applicationSer. No. 13/230,196, filed on Sep. 12, 2011, which claims priority toJapanese Application No. 2011-046924, filed Mar. 3, 2011, JapaneseApplication No. 2011-046926, filed Mar. 3, 2011, Japanese ApplicationNo. 2011-042939, filed Feb. 28, 2011, Japanese Application No.2011-042930, filed Feb. 28, 2011, Japanese Application No. 2011-042950,filed Feb. 28, 2011, and Japanese Application No. 2010-206137, filedSep. 14, 2010. The disclosures of these documents, including thespecifications, drawings and claims, are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a molding apparatus and a moldingmethod for molding a resin molded product.

2. Background Art

The following methods are methods of molding a duct, which is an exampleof a resin molded product. Two pre-molded sheets are reheated and placedin a molten state between a pair of upper and lower molds. After this, apressurized liquid is blown in between the two sheets, while closing andadjusting the pair of molds. Consequently, a climate control duct isformed in which the first half and the second half are joined as asingle unit.

Furthermore, for example, a sheet blow molding method using a foamedresin sheet is disclosed in JP-A 2001-239824 (Patent Document 1) andJP-A 2000-289093 (Patent Document 2). In the sheet blow molding method,two thermoplastic resin sheets cut in a predetermined size in advanceare heated with an infrared heater and softened. Next, the sheet ispinched-off from the mold. Then, the sheet is attached firmly to thesurface of the cavity by the blowing of a pressurized fluid between thesheets. Due to this, the sheet is molded into the desired shape.

However, in the sheet blow molding method mentioned above, sheetsprepared in advance in room temperature are softened during sheet blowmolding by reheating it with radiant heat sources such as infraredheaters. Therefore, for example, when foamed resin sheets are used, itis difficult for the sheet to be in a uniform molten state including itsinternal mass. In addition to this, when compared with molten andextruded sheets, the reheated sheets contain less heat. Therefore, notonly does this cause poor traceability for the sheet along the mold'scavity, but also inadequate adhesion at each pinched-off section(parting line) of the two sheets. Given this situation, it is desirableto improve the adhesion of the sheets.

Furthermore, WO 2009/157197 (Patent Document 3) is an example of therelated art by the present applicant. A molding apparatus of molding aresin molded product using a molten thermoplastic resin sheet isdisclosed in this document.

Further, in the molding apparatus disclosed in the above mentionedPatent Document 3, the thermoplastic resin is intermittently extruded,in a predetermined extrusion amount per unit time, from the extrusionslit with a fixed gap provided on the T-Die. This extrusion is performedat a predetermined extrusion rate, such that the molten thermoplasticresin sheet suspends downward. Then, the thermoplastic resin sheetextruded downward is passed between a pair of rollers. The thermoplasticresin sheet is compressed between these rollers by narrowing thedistance between this pair of rollers. Then, by rotating the pair ofrollers, the thermoplastic resin sheet is sent downward. While sendingthe thermoplastic resin sheet through the pair of rollers, the rotationspeed of the pair of rollers is adjusted so that the transmission rateof the thermoplastic resin sheet from the pair of rollers is greaterthan the extrusion rate of the thermoplastic resin sheet being extrudedfrom the extrusion slit. Thus draw-down or necking-in of thethermoplastic resin sheet is effectively prevented. As a result, thethermoplastic resin sheet is formed with uniform thickness in theextruding direction. Furthermore, draw-down is the effect in which overa period of time, the molten sheet under its own weight gets stretched,and becomes thinner toward the upper part of the sheet. Also, necking-inis the effect in which the sheet width becomes lessened by contractionof the sheet due to draw-down in the width direction.

In the molding apparatus disclosed in the above Patent Document 3, aresin molded product is formed using the thermoplastic resin sheetextruded from the T-Die. Thus, the wave effect (curtain effect) mayoccur in the thermoplastic resin sheet extruded from the T-Die.

If the curtain effect occurs on the thermoplastic resin sheet, even whena frame comes in contact with the lateral surface of the thermoplasticresin sheet, a gap occurs between the thermoplastic resin sheet and theframe. Thus, it becomes impossible to form a closed space between thethermoplastic resin sheet, the frame, and the surface of the cavity.

Further, JP-A-06-99474 (Patent Document 4) and JP-A-54-112965 (PatentDocument 5) disclose the structure of a molding apparatus using frames.In these as well, problematic situations similar to those in PatentDocument 3 could occur.

SUMMARY

An object of the present invention is to provide a molding apparatus anda molding method, which can bring the frame positioned on the perimeterof the mold into proper contact with the thermoplastic resin.

<Molding Apparatus>

A molding apparatus of this invention is a molding apparatus thatadsorbs thermoplastic resin extruded in a sheet form from an extrudingmachine, onto a cavity surface of a mold, and shapes the thermoplasticresin into a shape according to the cavity surface, comprising

a frame that is positioned on a perimeter of the mold and is movablerelative to the mold, wherein

a suction part for sucking the thermoplastic resin is provided in theframe.

<Molding Method>

A molding method of this invention includes:

a sucking step in which air is sucked in from a suction part provided ina frame positioned on a perimeter of a mold so as to adsorbthermoplastic resin extruded from an extruding machine in a sheet formonto the frame, and to bond the thermoplastic resin to the frame; and

a shaping step in which the thermoplastic resin facing a cavity surfaceof the mold is adsorbed onto the cavity surface, to shape thethermoplastic resin into a shape according to the cavity surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration example of the molding apparatus whichimplements the molding method of a climate control duct in the presentembodiment;

FIG. 2 shows the process, wherein in the molding apparatus 1 shown inFIG. 1, a pair of thermoplastic foamed resin sheets is placed in a pairof split mold blocks, and the gap of the cavity surface of the splitmold block is closed by the frame;

FIG. 3 shows the vacuum adsorption process wherein, after the processshown in FIG. 2, each thermoplastic foamed resin sheet P is adsorbedonto the cavity surface of the split mold block by a vacuum;

FIG. 4 shows the molding process wherein, after the process shown inFIG. 3, the climate control duct is formed as a molded product by theclosing of the split mold blocks;

FIG. 5 shows the ejecting process wherein, after the process shown inFIG. 4, the split mold blocks open and the molded product of the climatecontrol ducts is ejected;

FIG. 6 is a perspective view of the climate control duct molded by themolding apparatus shown in FIG. 1;

FIG. 7 is an enlarged cross-sectional view of the climate control ductshown in FIG. 6;

FIG. 8 shows another configuration example of the molding apparatusimplementing the molding method of the climate control duct of thepresent embodiment;

FIG. 9 shows a structural example of the T-Die configuring the moldingapparatus and a structural example of the single manifold method;

FIG. 10 shows a structural example of the T-Die configuring the moldingapparatus and a structural example of the multi-manifold method;

FIG. 11 illustrates the example of a first embodiment;

FIG. 12 shows a configuration example of the molding apparatus in asecond embodiment;

FIGS. 13A, 13B, 13C, and 13D show a configuration example of the splitmold blocks and the frames in the second embodiment;

FIGS. 14A, 14B, and 14C are the first figures that show theconfiguration examples of the suction part;

FIG. 15 is the second figure showing the configuration example of thesuction part;

FIG. 16 shows the situation where the second frame comes into contactwith the thermoplastic resin sheet extruded from the T-Die in themolding apparatus shown in FIG. 12;

FIG. 17 shows the situation where the first frame comes into contactwith the thermoplastic resin sheet, following the situation shown inFIG. 16;

FIG. 18 shows the situation where the thermoplastic resin sheet isadsorbed by a vacuum onto the cavity surface of the split mold block,following the situation shown in FIG. 17;

FIG. 19 shows the situation where the split mold blocks are closed,following the situation shown in FIG. 18;

FIG. 20 shows the situation where the split mold blocks are opened,following the situation shown in FIG. 19;

FIG. 21 shows another configuration example of the molding apparatus inthe second embodiment;

FIGS. 22A, 22B, 22C, and 22D show the configuration example of agroove-shaped gap of the suction part;

FIG. 23 shows another configuration example of the molding apparatus inthe second embodiment;

FIG. 24 shows the configuration example of the molding apparatus in athird embodiment;

FIGS. 25A and 25B are the first figures showing the configurationexample of the split mold blocks and the frames in the third embodiment;

FIGS. 26A, 26B, 26C, and 26D are the second figures showing theconfiguration example of the split mold blocks and the frames in thethird embodiment;

FIG. 27 shows the situation where the frame has made contact with thethermoplastic resin sheet extruded from the T-Die, in the moldingapparatus shown in FIG. 24;

FIG. 28 shows the situation where the thermoplastic resin sheet isadsorbed by a vacuum onto the cavity surface of the split mold blocks,following the situation shown in FIG. 27;

FIG. 29 shows the situation where the split mold blocks are closed,following the situation shown in FIG. 28;

FIG. 30 shows the situation where the split mold blocks are opened,following the situation shown in FIG. 29; and

FIG. 31 shows another configuration example of the molding apparatus inthe third embodiment.

EXEMPLARY EMBODIMENTS First Embodiment An Overview of the Molding Methodof the Resin Molded Product in the First Embodiment

First, an overview of the molding method of the resin molded product inthe present embodiment is explained with reference to FIGS. 1 through 4.

The molding method of the resin molded product in the present embodimentis implemented using a molding apparatus 1, as shown in FIG. 1. First,as shown in FIG. 1, a molten thermoplastic resin sheet P is placedbetween split mold blocks 32A and 32B.

Next, as shown in FIG. 2, air is sucked by a suction part (not shown)provided in a frame 33A (33B) located on the perimeter of the split moldblock 32A (32B). Thus, the thermoplastic resin sheet P is adsorbed ontothe frame 33A (33B). Thus, the thermoplastic resin sheet P gets bondedto the frame 33A (33B).

Next, as shown in FIG. 3, the thermoplastic resin sheet P is adsorbedonto cavity surfaces 116A and 116B of the split mold blocks 32A and 32B.Moreover, as shown in FIG. 4, the split mold blocks 32A and 32B areclosed. Thus, the resin molded product is formed.

In the molding method of the resin molded product in the presentembodiment, air is sucked by the suction part provided in the frame 33A(33B). Due to this, the thermoplastic resin sheet P is adsorbed onto theframe 33A (33B). Thus, the thermoplastic resin sheet P attaches firmlyto the frame 33A (33B). This allows the frame 33A (33B) to make securecontact with the thermoplastic resin sheet P.

Also, the molding method of the resin molded product of the presentembodiment, molds the resin molded product by placing the moltenthermoplastic resin sheet P between the split mold blocks 32A and 32B,and closing the split mold blocks 32A and 32B. This improves theadhesion of the thermoplastic resin sheet P. Below, the molding methodof the resin molded product of the present embodiment, is explained indetail with reference to the attached drawings. Further, in thefollowing embodiment, the molding method of a climate control duct 18,which is an example of the resin molded product, is described using anexample.

<Example of Molding Method of Climate Control Duct 18>

First, with reference to FIGS. 1 through 5, an example of a moldingmethod of a climate control duct 18 as shown in FIGS. 6 and 7 isexplained. FIG. 1 is a configuration example of the molding apparatus100 that molds the climate control duct 18 as shown in FIGS. 6 and 7.FIGS. 2 through 5 illustrate the molding processes of the climatecontrol duct 18.

The climate control duct 18, as shown in FIGS. 6 and 7, is a lightweightclimate control duct used for ventilation of climate controlled air,supplied by an air conditioning unit, to a desired location. The climatecontrol duct 18 of this present embodiment has foamed wall surfaces (afirst wall 19 and a second wall 20, in the same manner below). Thesewall surfaces have closed air cell structures (closed air cell ratios of70% or more), which contain a plurality of air cells (having anexpansion ratio of 2.0 times or more). Moreover, the climate controlduct 18 includes a parting line 21 and a fitting piece 22. The climatecontrol duct 18 of this present embodiment is attached to other partswith the fitting piece 22.

The average wall thickness of the walls 19 and 20 of the climate controlduct 18 in the present embodiment is 3.5 mm or less. The averagediameter of the air cells of the walls 19 and 20, in thicknessdirection, is less than 300 μm, preferably less than 100 μm.

The material of the climate control duct 18 in this present embodimentmay be a polypropylene type resin. Preferably, this material should be ablended resin of polyethylene type resin and polypropylene type resin.The preferred tensile fracturing elongation of the material for theclimate control duct 18 should be 40% or more at −10° C. Moreover, atensile elasticity of 1000 kg/cm³ or more at room temperature ispreferred for this material. In addition to this, the tensile fracturingelongation of this material is preferably 100% or more at −10° C. Themeasuring methods of the material characteristics and the definitions ofthe expansion ratio are shown below.

Tensile fracturing elongation: The walls 19 and 20 of the climatecontrol duct 18 obtained from the molding method of the presentembodiment were cut and stored at −10° C. After this, from this cutportion, specimen No. 2 was shaped in accordance with JIS K-7113 (ISO527). The tensile fracturing elongation of this specimen was measured byapplying tension at a rate of 50 mm/minute.

Tensile elasticity: The walls 19 and 20 of the climate control duct 18obtained from the molding method of the present embodiment were cut.Using this cut portion, specimen No. 2 was shaped in accordance with JISK-7113 in room temperature (23° C.). The tensile elasticity of thisspecimen was measured by applying tension at a rate of 50 mm/minute.

Expansion ratio: Expansion ratios were determined by dividing thedensity of the thermoplastic resin used in the molding method of thepresent embodiment by the apparent density of walls 19 and 20 of theclimate control duct 18 obtained from the molding method of the presentembodiment.

Melt flow rate (MFR): Measured with testing temperatures at 230° C., anda test load of 2.16 kg, in accordance with JIS K-7210 (ISO 1133).

Izod impact strength: The walls 19 and 20 of the climate control duct 18obtained from the molding method of the present embodiment were cut andstored at −20° C. After this, several small pieces measuring 80×10(length×breadth in mm) were cut. These sheets were layered to form a 4mm thickness, and used as a specimen. This specimen was used formeasurement, in accordance with JIS K-7110 (ISO 180) (notched).

<A Configuration Example of Molding Apparatus 100>

First, with reference to FIG. 1, a configuration example of the moldingapparatus 100 for molding the climate control duct 18 in the presentembodiment is explained.

The molding apparatus 100 as shown in FIG. 1 has an extruding machine 12and a clamping machine 10. Two molten thermoplastic foamed resin sheetsP are extruded from the extruding machine 12 to the clamping machine 10.In the clamping machine 10, the two molten thermoplastic foamed resinsheets P are placed between a pair of split mold blocks. The two sheetsadhere on the inner surfaces (surfaces of the cavity) of the split moldblocks by the closing of these molds. Through this, the climate controlduct 18, as shown in FIGS. 6 and 7, is formed.

The extruding machine 12 includes: a first accumulator 22A, a secondaccumulator 22B, a first plunger 24A, a second plunger 24B, a firstT-Die 28A, a second T-Die 28B, a first cylinder 18A, a second cylinder18B, a first thermoplastic resin supply hopper 16A, a secondthermoplastic resin supply hopper 16B, a first pair of rollers 30AA and30AB, a second pair of rollers 30BA and 30BB, a first electric motor20A, and a second electric motor 20B.

The clamping machine 10 includes the split mold blocks 32A and 32B, andthe frames 33A and 33B. The frame 33A (33B) is positioned at theperimeter of the split mold block 32A (32B). The split mold block 32A(32B) contains a cavity surface 116A (116B) and a pinch-off molding part118. The gap between the split mold block 32A (32B) and the frame 33A(33B) should preferably be 0.1 mm or more and less than 1.0 mm, morepreferably 0.1 mm or more and less than 0.5 mm. Setting such gaps canprevent the clogging of resins in the gap between the split mold block32A (32B) and the frame 33A (33B), as well as hindrance in the functionof the split mold block 32A (32B) and the frame 33A (33B) in cases ofthermal expansion.

<Molding Process Example of Climate Control Duct 18>

Next, the molding process example of the climate control duct 18 isexplained, with reference to FIGS. 1 through 5.

First, as shown in FIG. 1, two thermoplastic foamed resin sheets P(molten thermoplastic foamed resin sheets containing air cells) areextruded from the first T-Die 28A and the second T-Die 28B, in order toform the first wall 19 and the second wall 20. The two thermoplasticfoamed resin sheets P are suspended between the pair of the split moldblock 32A and the split mold block 32B.

Next, the frame 33A (33B) and the split mold block 32A (32B) are movedforward horizontally. Due to this, as shown in FIG. 2, the frame 33A(33B) located at the perimeter of the pair of the split mold block 32A(32B) come into contact with thermoplastic foamed resin sheets P. Then,the thermoplastic foamed resin sheets P are sucked in by a suction part(not illustrated) built into the frame 33A (33B). This allows the sheetsP to be retained on the frame 33A (33B). Also, this can allow shaping ofa closed space between the thermoplastic foamed resin sheets P and thecavity surface 116A (116B) of the split mold block 32A (32B).

Next, while the thermoplastic foamed resin sheets P are retained on theframe 33A (33B), the split mold block 32A (32B) is moved forwardhorizontally. Moreover, as shown in FIG. 3, the thermoplastic foamedresin sheets P are vacuum-adsorbed onto the cavity surface 116A (116B)of the split mold block 32A (32B). This shapes the thermoplastic foamedresin sheets P according to the cavity surface 116A (116B).

Next, the frame 33A (33B) and the split mold block 32A (32B) are movedforward horizontally. By this, as shown in FIG. 4, the frame 33A and thesplit mold block 32A, and the frame 33B and the split mold block 32B areclosed together. Due to this, the pinch-off molding parts 118 of thepair of split mold blocks 32A and 32B come into contact with each other.Consequently, the two thermoplastic foamed resin sheets P bond andthermally fuse, forming a parting line along the bonding surface of thetwo thermoplastic foamed resin sheets P. In this way, the molded productof the climate control duct 18 is formed.

Furthermore, after closing the split mold blocks 32A and 32B, air may beblown between the sheets P. The blow of air, for example, can be appliedwith a pressure between 1 and 3 kgf/cm². This allows greater accuracy inshaping the duct to correspond to the shape of the mold.

Next, the molded product of the climate control duct 18 is cooled withinthe pair of split mold blocks 32A and 32B.

Next, the frame 33A and the split mold block 32A, and the frame 33B andthe split mold block 32B are moved backward horizontally. Due to this,as shown in FIG. 5, the frame 33A and the split mold block 32A, and theframe 33B and the split mold block 32B, are separated from the moldedproduct of the climate control duct 18.

Next, the burrs along the perimeter of the parting line, formed by thepinch-off molding part 118, are removed. The result is the climatecontrol duct 18, as shown in FIGS. 6 and 7.

Furthermore, the thickness, extrusion speed, and wall thicknessdistribution of extrusion directions of the two thermoplastic foamedresin sheets P hung between the pair of split mold blocks 32A and 32B,are adjusted individually to prevent variances of the wall thicknessthat occur due to draw-down and necking-in.

Each expanded thermoplastic foamed resin sheet P is formed as follows.The thermoplastic foamed resin with an added foaming agent is melted andmixed by the first cylinder 18A and the second cylinder 18B. Next, thethermoplastic foamed resin sheet is temporarily stored in anaccumulation chamber of the first accumulator 22A, and an accumulationchamber of the second accumulator 22B. This thermoplastic foamed resinis supplied to the first T-Die 28A by the first plunger 24A and to thesecond T-Die 28B by the second plunger 24B, at a fixed interval. Inaddition to this, it is also possible to mix into the thermoplasticfoamed resin, for example, a foam nucleating agent or a coloring pigment(carbon black), to act as the foaming source in the first cylinder 18Aand the second cylinder 18B.

The thermoplastic foamed resin sheets P extruded from the first T-Die28A and the second T-Die 28B are compressed respectively, by the firstpair of rollers 30AA and 30AB, and the second pair of rollers 30BB and30BA. With these rollers, the thermoplastic foamed resin sheets P areplaced between the pair of the split mold block 32A and the split moldblock 32B. During this procedure, the thickness and the wall thicknessdistribution of each thermoplastic foamed resin sheet P are individuallyadjusted.

To be specific, first, the extrusion speed of each thermoplastic foamedresin sheet P is set individually, by the first accumulator 22A and thesecond accumulator 22B, and the first T-Die 28A and the second T-Die28B.

It is possible to appropriately select the extrusion capacity of thefirst cylinder 18A and the second cylinder 18B connected respectively tothe first accumulator 22A and the second accumulator 22B, according tothe size of the climate control duct 18 to be finally molded. However,an extrusion capacity of 50 kg/hour or more is preferred for the firstcylinder 18A and the second cylinder 18B. This makes it possible toshorten the molding cycle of the climate control duct 18.

Also, for preventing draw-down, extrusion of the thermoplastic foamedresin sheets P from the first T-Die 28A and the second T-Die 28B needsto be completed in 40 seconds or less, preferably in 30 seconds or less.

For this reason, the thermoplastic foamed resin, retained in theaccumulation chamber of the first accumulator 22A and the accumulationchamber of the second accumulator 22B, should be extruded through theslit opening of the first T-Die 28A and the second T-Die 28B at 50kg/hour or more per 1 cm², preferably at 60 kg/hour or more. Duringthis, draw-down can be kept minimal by changing the slit gaps of thefirst T-Die 28A and the second T-Die 28B along with the extrusion of thethermoplastic foamed resin sheets P.

In short, the thickness of the upper wall of the thermoplastic foamedresin sheets P tends to be thinner, as it becomes stretched by its ownweight due to the draw-down effect. On the other hand, the slit openingsof the first T-Die 28A and the second T-Die 28B corresponding to theupper part of thermoplastic foamed resin sheets P, can be graduallywidened as extrusion of the resin sheet P takes place. By doing this,the wall thickness of thermoplastic foamed resin sheets P can beadjusted to be uniform from top to bottom.

Additionally, it is also possible to differentiate the extrusion speedof the thermoplastic foamed resin sheets P being extruded from the firstT-Die 28A and the second T-Die 28B, and the rotation speed of the firstpair of rollers 30AA and 30AB, and the second pair of rollers 30BB and30BA. This then allows a difference to be set between the extrusionspeed of the thermoplastic foamed resin sheets P from the first T-Die28A and the second T-Die 28B, and the feeding rate of the thermoplasticfoamed resin sheets P from the first pair of rollers 30AA and 30AB, andthe second pair of rollers 30BB and 30BA. Consequently, thethermoplastic foamed resin sheets P can be expanded between the firstT-Die 28A and the second T-Die 28B, and the first pair of rollers 30AAand 30AB and the second pair of rollers 30BB and 30BA. As a result,thickness of the resin sheets P can be adjusted to be smaller.

Each thermoplastic foamed resin supplied to the first T-Die 28A and thesecond T-Die 28B is extruded from the slit of the T-Die body as thethermoplastic foamed resin sheets P, after passing through resin ductsstarting from the manifold of each T-Die body (not illustrated). TheT-Die body is made by overlapping a die upon another die. In the tip ofthe T-Die body, one die lip and another die lip face each other with agap therebetween. This slit gap is set by using a slit gap adjustmentdevice 23.

The thicknesses of the resin sheets P extruded from the first T-Die 28Aand the second T-Die 28B are determined by the slit gap. Specifically,the thickness of each thermoplastic foamed resin sheet P extruded fromthe first T-Die 28A and the second T-Die 28B is 0.6 to 6.0 mm.

Moreover, the slit gap is adjusted by a known slit gap adjustment device23. Uniformity in the width direction of the resin sheets P is adjustedby making adjustments on the slit gap. In addition to this, another dielip is altered by the slit gap adjustment device 23, during intermittentextrusion of the resin sheet P from beginning to end. Due to this, thethicknesses in the extruding direction of the resin sheets P areadjusted.

A thermal expansion device and a mechanical device are available for theslit gap adjustment device 23. It is preferable to use the slit gapadjustment device 23 equipped with both functions.

A plurality of slit gap adjustment devices 23 are placed at equalintervals along the width of the slit. The thickness of the resin sheetP can be made uniform along the entire width, by the narrowing orwidening of corresponding slit gaps with each slit gap adjustment device23.

The slit gap adjustment device 23 includes a die bolt set to freely movetoward or away from a die lip. An adjustment shaft is placed, throughthe pressure transmission part, at the tip of the die bolt. On theadjustment shaft, clutch pieces are fastened with tie bolts. The clutchpieces are linked to one die lip. As the die bolt moves forward, theadjustment shaft is pushed toward the tip through the pressuretransmission part. Consequently, the die lip is pressed. Subsequently,the die lip is deformed by the sections grooved in. For this reason, theslit gaps become narrow. On the contrary, in order to widen the slitgap, the die bolt is slid backward.

Additionally, the slit gap can be adjusted more precisely byimplementing a thermal expansion adjustment device, in addition to theabove mentioned mechanical adjustment device. More specifically, the dielip is pressed due to the thermal expansion of the adjustment shaftbeing heated by an electric heater, not shown. This causes narrowing ofthe slit gap.

Moreover, to widen the slit gap, the electric heater is stopped, and theadjustment shaft is cooled by cooling procedures not illustrated. Thiscauses the adjustment shaft to shrink, making the slit gap wider.

At the time when the resin sheet P extruded from the first T-Die 28A andthe second T-Die 28B is suspended between the pair of the split moldblock 32A and the split mold block 32B, or when the split mold block 32Aand the split mold block 32B are closed, it is preferable that thethickness in the extruding direction of the resin sheet P be adjusted tobe uniform. In such a case, the slit gap widens gradually as extrusionof the resin sheet P takes place, and reaches its maximum when extrusionof the resin sheet P ends.

Consequently, the thickness of the resin sheets P extruded from thefirst T-Die 28A and the second T-Die 28B gradually becomes thicker afterthe extrusion of the resin sheets P begin. However, as the resin sheet Pextruded in the molten state stretches due to its own weight (draw-downeffect), thickness of the resin sheet P tends to gradually becomethinner toward the upper section. Therefore, the thickness gained bywidened slit gaps, and the thinner area due to the draw-down effect,balance each other out. This allows the thickness of the resin sheet Pto be adjusted uniformly from top to bottom.

As mentioned above, if the pressure (injection pressure) when extrudingthe resin sheet P from the T-Die, the extrusion speed (injection speed)of the resin, the roller rotation speed, and the slit gap of the T-Die,are constant during injection, the extruded resin sheet P willexperience drawdown (necking) due to its own weight. Hence, as lowersections of the resin sheet P become thicker, upper sections on theother hand tend to become thinner. Therefore, the thickness of the resinsheet P can be adjusted by multiple-stage settings of injectionpressure, injection speed, and roller feeding speed, during injection.More specifically, upper sections of the resin sheet P being thinner canbe controlled by gradually raising the injection pressure and injectionspeed during injection. Also, the necking of the resin sheet P due toits own weight can be controlled by increasing the rotation speed(feeding speed) of the roller during injection.

These parameters (injection pressure, injection speed, roller rotationspeed) are relatively easy to adjust by controlling the cylinder and theaccumulator with a program. Therefore, these parameters are suitable foradjusting the wall thickness of the resin sheet P.

Moreover, when the material of the resin sheet P is a resin with highmembrane forming properties (for example, a resin in which inorganicfiller such as talc is added to a polypropylene type resin), uniformthickness of the resin sheet P can be obtained without making majoradjustments to injection pressure, injection speed, and roller rotationspeed, during injection.

Moreover, in the molding apparatus 100 illustrated in FIG. 1 mentionedabove, supply ducts of the thermoplastic foamed resin for the firstT-Die 28A and the second T-Die 28B are independent. However, as shown inFIG. 8, it is also possible to connect a single cylinder 18 and a singleaccumulator 22 connected to the cylinder 18, to the first T-Die 28A andthe second T-Die 28B. In such a case, branching at the tip of theaccumulator 22 will allow supply of thermoplastic foamed resin into thefirst T-Die 28A and the second T-Die 28B. In addition to this, anaccumulator using the side-accumulation method or ring-accumulationmethod can be used as the accumulator 22.

Moreover, the structure illustrated in FIG. 9 is also acceptable for thefirst T-Die 28A and the second T-Die 28B, as illustrated in FIG. 1 orFIG. 8. For example, when the second T-Die 28B is of the structureillustrated in FIG. 9, the thermoplastic foamed resin supplied from thesecond accumulator 22B is introduced and guided to a duct 71, and widensin the direction of the die width while flowing in a manifold 72. Next,the thermoplastic foamed resin heads toward a slit 73, through thedownstream resin duct of the manifold 72. Consequently, thethermoplastic foamed resin sheet P is suspended, between the pair of thesplit mold block 32A and the split mold block 32B, from the slit 73.

Moreover, the structure illustrated in FIG. 9 has gating mechanisms 74and 75 to control the gating of the slit 73. Sliding the gatingmechanisms 74 and 75 sideways will open or close the slit 73. Normally,closing of the outlet of the accumulation chamber of the accumulator 22A(22B) allows storing of the molten resin in the concerned accumulationchamber. Due to this, resin pressure in the accumulation chamber can beincreased. On the other hand, in the structure illustrated in FIG. 9,while increasing resin pressure, the tip of the T-Die is closed with aconnected state of the accumulation chamber and the duct within theT-Die. This allows the pressure of the resin stored in the accumulationchamber and the duct within the T-Die to be increased. In other words,pressure of the molten resin up to the outlet of the T-Die 28A (28B) canbe increased by closing the slit 73 using the gating mechanisms 74 and75. Next, when the internal pressure of the T-Die 28A (28B) increases toa specific value, the slit 73 is opened with the gating mechanisms 74and 75. Due to this, the thermoplastic foamed resin sheet P is suspendedfrom the slit 73, between the pair of the split mold block 32A and thesplit mold block 32B. In this way, the internal pressure within theT-Die 28A (28B) can be increased in this structure. Therefore, expansionof the thermoplastic foamed resin sheet P can be prevented until thethermoplastic foamed resin sheet P is extruded from the T-Die 28A (28B).The thermoplastic foamed resin sheet P can expand once the thermoplasticfoamed resin sheet P is extruded from the T-Die 28A (28B). Additionally,as long as the gating of the slit 73 is possible, any configuration orcontrol method is acceptable for the configuration and control method ofthe gating mechanisms 74 and 75. Also, a choke bar (not illustrated) mayalso be mounted downstream in the resin duct of the manifold 72. In thisstructure, the flow rate and thickness of the thermoplastic foamed resinin its width direction can be adjusted by the choke bar.

Moreover, the two thermoplastic foamed resin sheets P are suspendedbetween the pair of the split mold blocks 32A and 32B in the moldingapparatus 100 illustrated in FIG. 1 or FIG. 8, with the two T-Dies 28Aand 28B using the single manifold method. However, it is also possibleto suspend the two thermoplastic foamed resin sheets P between the pairof the split mold block 32A and the split mold block 32B using a singleT-Die 28B′ using the multiple manifold method illustrated in FIG. 10. Inthe T-Die 28B′ illustrated in FIG. 10, the thermoplastic foamed resinsupplied from the accumulator 22 is introduced and guided into the twoducts 61 and 61. The thermoplastic foamed resin flows through eachmanifold 62 and 62, and spreads along the width of the die. Choke bars63 and 63 are set downstream in the manifolds 62 and 62. The flow ratein width and the thickness of the thermoplastic foamed resin can beadjusted with this choke bar 63. This enables two thermoplastic foamedresin sheets P to be suspended between the pair of the split mold block32A and the split mold block 32B, from the T-Die 28B′ illustrated inFIG. 10. Moreover, the internal pressure of the T-Die 28B′ can beincreased by closing the resin duct using the choke bars 63 and 63.Since this allows an increase in internal pressure of the T-Die 28B′,the expansion of the thermoplastic foamed resin sheet P can be preventeduntil the thermoplastic foamed resin sheet P is extruded from the T-Die28B′. The thermoplastic foamed resin sheet P can expand, once thethermoplastic foamed resin sheet P is extruded from the T-Die 28B′.

Moreover, in the molding apparatus 100 illustrated in FIG. 1 or FIG. 8,the first pair of rollers 30AA and 30AB, and the second pair of rollers30BB and 30BA adjust the thickness of the thermoplastic foamed resinsheet P. However, these pairs of rollers are not indispensable.

When the thermoplastic foamed resin sheet P is compressed by the pair ofrollers, the air cells in the thermoplastic foamed resin sheet P mayburst. Therefore, in a structure without a pair of rollers, since theair cells in the thermoplastic foamed resin sheet P do not burst, theexpansion ratio of the thermoplastic foamed resin sheet P can beincreased.

The polypropylene type resin, available for use in molding of theclimate control duct 18 in the present embodiment, is preferablypolypropylene having a melt tension within the range of 30 to 350 mN at230° C. Especially, the polypropylene type resin preferably is apolypropylene homopolymer having a long chain branching structure, andthe one with additives of ethylene-propylene block copolymer is evenbetter.

Moreover, hydrogenated styrene thermoplastic elastomer may also be addedto the polypropylene type resin. In such a case, in order to maintainstiffness and improve impact-resistance of the climate control duct 18,styrene thermoplastic elastomer is added to the polypropylene type resinat 5 to 40 wt %, preferably within the range of 15 to 30 wt %.

The styrene thermoplastic elastomer used, specifically, is ahydrogenated polymer of styrene-butadiene-styrene block copolymer,styrene-isoprene-styrene block copolymer, and styrene-butadiene randomcopolymers. Moreover, when using a hydrogenated styrene thermoplasticelastomer, the styrene content is less than 30 wt %, preferably lessthan 20 wt %. The MFR (measured under the testing temperature of 230°C., and a testing load of 2.16 kg, in accordance with JIS K-7210) of thehydrogenated styrene thermoplastic elastomer at 230° C., is 10 g/10minutes or less, preferably 5.0 g/10 minutes or less and 1.0 g/10minutes or more.

Moreover, the polyolefin polymer added to the polypropylene type resinis preferably a low density ethylene-α-olefin, with a preferredcompounding ratio within the range of 1 to 20 wt %. The low densityethylene-α-olefin preferably should have a density of 0.91 g/cm³ orless. A suitable low density ethylene-α-olefin is the ethylene-α-olefincopolymer obtained by copolymerizing α-olefin having 3 to 20 carbonatoms, with ethylene. Some examples are propylene, 1-butane, 1-pentene,1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene,4-methyl-1-pentene, 4-methyl-1-hexene, and 1-butane, 1-hexane, and1-octene are preferred. Moreover, α-olefin with 3 to 20 carbon atoms asmentioned above can be used independently, and also in combinations oftwo or more types. The content of the monomer unit based on ethylene ofthe ethylene-α-olefin copolymer, in relation to the ethylene-α-olefincopolymer, is within the range of 50 to 99 wt %. Moreover, the contentof the monomer unit based on α-olefin is in the range of 1 to 50 wt %,in relation to the ethylene-α-olefin copolymer. Specifically, use oflinear very-low density polyethylene, ethylene elastomer, or propyleneelastomer, polymerized using a metallocene catalyst, is preferred.

The material of the thermoplastic foamed resin sheet P, suspendedbetween the pair of the split mold block 32A and the split mold block32B, needs to have a high melting tension. Not only does this preventvariances in the wall thickness of the resin sheet P caused by draw-downor necking-in, but can also increase the expansion ratio. For thisreason, the climate control duct 18 is produced with excellentlight-weight and insulation properties.

In particular, the MFR of the resin sheet P at 230° C. (measured underthe testing temperature of 230° C., and a testing load of 2.16 kg inaccordance with JIS K-7210), is preferably 5.0 g/10 minutes or less,more preferably 1.5 to 3.0 g/10 minutes. Now generally, the MFR at 230°C. (measured under the testing temperature of 230° C., and a testingload of 2.16 kg, in accordance with JIS K-7210) of resin materials usedin shaping films and the like through extrusion from a T-Die, is greaterthan 3.0 g/10 minutes, specifically 5.0 to 10.0 g/10 minutes.

Moreover, it is also possible to use a blended resin as the material ofthe resin sheet P for molding the climate control duct 18 in the presentembodiment, where a long chain branch structured polypropylene(mentioned hereafter as long chained PP) and a polyethylene resincontaining a high density polyethylene with a long chain branchstructure (mentioned hereafter as long chained HDPE) are blended.

Also, the polyethylene resin containing the long chained HDPE maycontain only the long chained HDPE, or may also be a blended material ofthe long chained HDPE with other polyethylene type resins. For example,polyethylene (low density polyethylene, medium density polyethylene orthe like) with a density of 0.94 g/cm³ or less, may be blended in thelong chained HDPE.

Molding the climate control duct 18 using the above mentioned resinblend, results in a high expansion form of the climate control duct 18.

Moreover, from the perspective of increasing the expansion ratio, it ispreferred that the long chained PP be a propylene homopolymer (homo PP)with a weighted average branching index of 0.9 or less. Also, theweighted average branching index is represented by v1/v2 where v1 is theviscosity limit value of the branched polyolefin, and v2 is theviscosity limit value of the linear polyolefin having the sameweight-average molecular weight as the branched polyolefin.

Again, from the perspective of increasing the expansion ratio, it ispreferred that the long chained HDPE be an ethylene homopolymer (homoPE) with a melt tension (MT) at 230° C. of 30 mN or more.

Moreover, from the perspective of maintaining stiffness while increasingde-burring performance, a high density polyethylene (density of 0.94g/cm³ or more) of a non-long chained branching structure can be used asthe polyethylene other than the long chained HDPE, to be blended in theresin blend. Further, in order to increase impact resistance in lowtemperatures, a polyethylene with a density of 0.91 g/cm³ or less mayalso be used. In this case, it is especially preferred that a very-lowdensity linear polyethylene, polymerized by a metallocene catalyst, beused.

Moreover, it is preferred that several resins be blended in the resinblend, to have a melt tension (MT) at 230° C. of 30 to 350 mN. Here, MTrefers to the melting tension. If the MT of the resin blend is withinthe range of 30 to 350 mN, a high expansion ratio can be obtained. Inaddition to this, MT is the tension measured by using the “melt tensiontester” (manufactured by Toyo Seiki Seisaku-sho Ltd). In thismeasurement, the pre-heating temperature is 230° C. and the extrusionspeed is 5.7 mm/minute, and the strand is extruded from an orificemeasuring 2.095 mm in diameter and 8 mm in length. This strand is woundat a winding speed of 100 rpm, onto a roller of 50 mm diameter. The MTis measured as the strand tension during this winding.

Moreover, the melt flow rate (MFR) at 230° C. of the resin blend ispreferably 1 to 10 g/10 minutes. Here, the MFR refers to the valuemeasured according to JIS K-7210. When compared to when the MFR iswithin the range of 1 to 10 g/10 minutes, if the MFR is less than 1 g/10minutes, it tends to become more difficult to increase the extrusionspeed. When compared to when the MFR is within the range of 1 to 10 g/10minutes, if the MFR exceeds 10 g/10 minutes, molding tends to be moredifficult due to draw-down occurring.

Moreover, the expansion ratio can be increased by shaping a foamedmolding using a resin blend containing 5 to 40 wt % of thermoplasticelastomer. In this case, for example, styrene elastomer, ethylenepropylene rubber (mentioned hereafter as EPR), and olefin blockcopolymer (mentioned hereafter as OBC) can be used as the thermoplasticelastomer.

As a styrene elastomer, it is possible to use an elastomer having astyrene unit with hydrogen added within molecules. For example, it ispossible to use hydrogenated elastomers such asstyrene-ethylene-butylene-styrene block copolymer (mentioned hereafteras SEBS), styrene-ethylene-propylene-styrene block copolymer, andstyrene-butadiene random copolymers.

Moreover, by molding the climate control duct 18 using a resin blendcontaining 5 to 20 wt % of OBC (olefin block polymer), the expansionratio can be increased approximately 4.0 times or more. Note that theOBC is a product in which the two types of polyolefins are alternatelyshaped into blocks within a single molecule, through a catalyst systeminvolving two types of catalysts.

As a foaming agent, inorganic physical foaming agents such as air,carbon dioxide, nitrogen gas, and water, and organic physical foamingagents such as butane, pentane, hexane, dichloromethane, anddichloroethane, chemical foaming agents such as sodium bicarbonate,citric acid, sodium citrate, and azodicarbonamide (mentioned hereafteras ADCA), or in addition to this, a combination of these physicalfoaming agents and chemical foaming agents, can be used as the foamingagent.

Especially, using a chemical foaming agent that produces a carbondioxide gas, such as carbon dioxide, sodium bicarbonate, citric acid, orsodium citrate as a foaming agent, can control shark-skin fromoccurring. This then creates a clean surface on the foamed molding.Here, shark-skin refers to the irregularities on the surface of themolded product due to the uneven flow of the molten resin from the dieslits.

Moreover, the chemical foaming agent plays a core role in the foaming ofthe physical foaming agent, when a combination of carbon dioxide as aphysical foaming agent, and a chemical foaming agent generating carbondioxide, is used. This enables fine dispersion of air cells. Thus, thestrength of the foamed molding can be increased, while improvingde-burring performance.

Moreover, when mixing a physical foaming agent into the resin blend, itis preferable to mix the physical foaming agent as a supercritical fluidinto the resin blend. Especially, it is preferable to mix carbon dioxideor nitrogen gas in its supercritical state, into the resin blend. Inthis case, uniform and assured foaming is obtained. Moreover, fornitrogen, the supercritical fluid state of nitrogen can be obtained bysetting the critical temperature at −149.1° C., and critical pressure of3.4 MPa or more. The supercritical fluid state of carbon dioxide isobtained by a critical temperature of 31° C., and critical pressure of7.4 MPa or more.

<Operation/Effect of the Molding Method of the Climate Control Duct 18in the Present Embodiment>

In this way, in the molding method of the climate control duct 18 in thepresent embodiment, the thermoplastic foamed resin mixed with a foamingagent and supplied from the cylinder 18A (18B), as shown in FIG. 1, isaccumulated in the accumulator 22A (22B). This thermoplastic foamedresin is supplied to the T-Die 28A (28B) at fixed intervals using theplunger 24A (24B). A pair of the thermoplastic foamed resin sheets P ina molten state containing air cells, is extruded from the T-Dies 28A and28B. This pair of thermoplastic foamed resin sheets P is placed betweenthe pair of the split mold block 32A and the split mold block 32B. Then,as shown in FIG. 2, air is sucked by the suction part (not shown)provided in the frame 33A (33B) that is located around the split moldblock 32A (32B). Thus, the thermoplastic foamed resin sheet P isattached firmly onto the frame 33A (33B). As a result, the thermoplasticfoamed resin sheet P is attached firmly to the frame 33A (33B). Next, asshown in FIG. 3, the thermoplastic foamed resin sheet P is adsorbed by avacuum onto the cavity surface 116A (116B) of the split mold block 32A(32B). Moreover, as shown in FIG. 4, the split mold block 32A and thesplit mold block 32B are closed. Thus, the climate control duct 18 ismolded. After that, as shown in FIG. 5, the pair of the split moldblocks 32A and 32B are separated from the climate control duct 18, andthe climate control duct 18 is removed.

In this way, in the molding method of the duct in the presentembodiment, the thermoplastic foamed resin sheet P is adsorbed onto theframe 33A (33B) by sucking air with the suction part (not shown)provided in the frame 33A (33B). Therefore, the thermoplastic foamedresin sheet P is attached firmly onto the frame 33A (33B). Thus, theframe 33A (33B) can make secure contact with the thermoplastic foamedresin sheet P.

Also, in the molding method of the duct in the present embodiment, apair of molten thermoplastic foamed resin sheets P is placed between thepair of the split mold blocks 32A and 32B. After that, the split moldblock 32A and the split mold block 32B are closed and the duct ismolded. Thus, the adhesion of the two thermoplastic foamed resin sheetsP can be improved.

EXAMPLES

Next, specific examples, related to an example of the molding method ofthe climate control duct 18 mentioned above are explained. However, thefollowing Examples are only some examples, and the technical concepts ofthe present embodiment are not limited to these following examples.

FIG. 11 shows (1) the material compound ratio of the resin blend, and(2) the expansion ratio of the molded foaming ducts, regarding Examples1 through 5.

The resins A to C shown in FIG. 11 and the following Examples correspondto the following resins.

Resin A: Long chained HDPE (homopolymer), “08S55A” made by TosohCorporation

Resin B: Long chained PP (homopolymer), “WB140” made by Borealis Inc.

Resin C: OBC, “OBC9000” made by the Dow Chemical Company

Example 1

A foamed resin was made by taking carbonic acid gas in its supercriticalstate as the foaming agent, talc master batch (1.5 parts by weight) asthe nucleating agent, and carbon black master batch (1.5 parts byweight) as the coloring agent, and adding them to the resin blend (100parts by weight) obtained by mixing Resin A and Resin B at a ratio of50:50. This was extruded between the split mold block 32A and the splitmold block 32B as two thermoplastic foamed resin sheets P. The splitmold block 32A and the split mold block 32B were closed, bonding andthermally fusing the two thermoplastic foamed resin sheets P. This formsthe molding of the climate control duct 18. As shown in FIG. 11, theexpansion ratio of the molded climate control duct 18 was 2.9 times.

Example 2

The procedures in Example 2 were the same as the procedures in Example1, except that the resin blend used was obtained by mixing Resin A,Resin B, and Resin C in a ratio of 50:45:5. As shown in FIG. 11, theexpansion ratio of the molded foamed duct was 4.2 times.

Example 3

The procedures in Example 3 were the same as the procedures in Example1, except that the resin blend used was obtained by mixing Resin A,Resin B, and Resin C in a ratio of 50:40:10. As shown in FIG. 11, theexpansion ratio of the molded foamed duct was 4.7 times.

Example 4

The procedures in Example 4 were the same as the procedures in Example1, except that the resin blend used was obtained by mixing Resin A,Resin B, and Resin C in a ratio of 50:30:20. As shown in FIG. 11, theexpansion ratio of the molded foamed duct was 4.0 times.

Example 5

The procedures in Example 5 were the same as the procedures in Example1, except that the resin blend used was obtained by mixing Resin A,Resin B, and Resin C in a ratio of 50:10:40. As shown in FIG. 11, theexpansion ratio of the molded foamed duct was 3.7 times.

Example 1 is a foamed resin blend with a polyethylene type resinincluding high density polyethylene (Resin A) of long chained branchingstructures at 50 wt %, and polypropylene (Resin B) of long chainedbranching structures at 50 wt %. The expansion ratio of such foamedresin blend will be higher than that of a resin blend in which onlypolypropylene (Resin B) with long chained branching structures isfoamed.

Moreover, according to Examples 2 through 5, blending of the OBC as athermoplastic elastomer at 5 to 40 wt % can cause improvements in theexpansion ratio, when compared to the blending of other thermoplasticelastomers.

Especially, according to Examples 2 to 4, blending OBC at 5 to 20 wt %is preferable as it causes an increase of the expansion ratio (4.0 timesor higher). What is even better, is to have OBC at around 10 wt % (8 to12 wt %). Consequently, the climate control duct 18 with high expansionratios approximately between 4.2 to 4.7 times can be obtained.

Moreover, the climate control duct 18 with an expansion ratio of 4.0times or more can easily be obtained by foamed molding of a resin blendproduced to have compounds of the long chained HDPE (homopolymer) at 40to 60 wt %, compounds of the long chained PP (homopolymer) at 30 to 45wt %, and compounds of OBC at 5 to 15 wt % (long chained HDPE, longchained PP, and OBC to total 100 wt %).

Moreover, the application of the climate control duct 18 in the presentembodiment is not limited to automobiles. Appropriately changing thedesign of the climate control duct 18 will allow for application of theclimate control duct 18 in carriers such as trains, ships and airplanes.The climate control duct 18 in the present embodiment is light-weightwhile having a certain degree of strength, and is able to bemanufactured at a low cost. Therefore, use of this climate control duct18 can reduce the cost of carriers as well as increasing fuel efficiencythereof.

Moreover, it is also possible to insert and mold the duct by placing afin to control wind direction, between the pair of sheets P extrudedfrom the extruding machine 12. With this, a duct having internal finscan be molded. In this procedure, a wider cross sectional area of theair passage can be secured by blow molding ribs controlling winddirection integrally with the duct, when compared to the procedure ofmolding ducts with unchanging contours. Due to this, drops in pressurecan be controlled.

Also, in the production method of the present embodiment mentionedabove, the resin sheet P is extruded downward from the T-Die 28A (28B)positioned above the split mold block 32A (32B). Next, the resin sheet Pis compressed between the split mold block 32A and the split mold block32B. A mechanism to maintain the resin sheet P becomes unnecessary withsuch method. Thus, the manufacturing device can be simplified. In otherwords, for example, a procedure where the resin sheet P is extrudedhorizontally from the T-Die 28A (28B) can also be considered. Afterthat, the sheet P is compressed from top and bottom by the split moldblock 32A and the split mold block 32B. However, under such method, amechanism to control slacking of the sheet P, while placing the sheet Pbetween the split mold block 32A and the split mold block 32B, would benecessary. On the other hand, in the production method of the presentembodiment mentioned above, the resin sheet P extruded from theextruding machine 12 is placed between the split mold block 32A and thesplit mold block 32B while its own weight prevents deflection. Thus, itis possible to mold a duct with a simple mechanism.

Moreover, in the method of the present embodiment mentioned above, thethermoplastic foamed resin sheet P is adsorbed and retained by the frame33A (33B). Therefore, a closed space can accurately be formed betweenthe thermoplastic foamed resin sheet P and the cavity surface 116A(116B) of the split mold block 32A (32B). Therefore, by sucking thesheet P from the cavity surface 116A (116B), the shape of the cavitysurface can be reflected in the sheet P more accurately.

Second Embodiment

The second embodiment is explained as follows.

<An Overview of the Molding Apparatus 1 in the Second Embodiment>

First, an overview of the molding apparatus 1 in the second embodimentis explained with reference to FIGS. 12, 13A, 13B, 13C, and 13D.

The molding apparatus 1 of the present embodiment has the extrudingmachine 12 and the clamping machine 10. The extruding machine 12extrudes the molten and mixed thermoplastic resin P in the sheet form.The clamping machine 10 contacts the thermoplastic resin P in the sheetform, extruded from the extruding machine 12, with the frame 33A (33B)which can move relative to the split mold block 32A (32B) and is locatedaround it. After that, the thermoplastic resin P facing the cavitysurface 116A (116B) of the split mold block 32A (32B) is adsorbed by avacuum onto the cavity surface 116A (116B). Thus, the thermoplasticresin P is shaped into the shape according to the cavity surface 116A(116B). Then, the split mold block 32A and the split mold block 32B areclosed. Thus, the resin molded product is formed.

As shown in FIG. 13A, a suction part 34 for sucking the thermoplasticresin P is provided on the contact surface 100, contacting thethermoplastic resin P, of the frame 33A (33B) of the molding apparatus 1in the present embodiment.

In the molding apparatus 1 of the present embodiment, air is sucked bythe suction part 34 provided in the frame 33A (33B). Therefore, thethermoplastic resin P in sheet form, extruded from the extruding machine12, is adsorbed onto the frame 33A (33B). Thus, the thermoplastic resinP can be attached firmly to the frame 33A (33B). This can prevent theoccurrence of gaps between the frame 33A (33B) and the thermoplasticresin P. Thus, the thermoplastic resin P can be shaped into the shapeaccording to the cavity surface 116A (116B). Below, the moldingapparatus 1 of the present embodiment is explained in detail withreference to the attached drawings.

<Configuration Example of the Molding Apparatus 1>

First, the configuration example of the molding apparatus 1 in thepresent embodiment is explained, with reference to FIGS. 12, 13A, 13B,13C, and 13D.

The molding apparatus 1 of the present embodiment is an apparatus tomold resin molded products, and includes the extruding machine 12 andthe clamping machine 10. The molten thermoplastic resin sheet P isextruded from the extruding machine 12 to the clamping machine 10. Inthe clamping machine 10, two thermoplastic resin sheets P are placedbetween the split mold block 32A and the split mold block 32B. The resinmolded product is molded by closing these mold blocks.

In the frame 33A (33B) of the present embodiment, as shown in FIGS. 13A,13B, 13C, and 13D, a central part 33A-2″ (201A) of a bottom frame 33A-2(refer to FIG. 12), which configures the lower side of the frame 33A, isseparated from the frame 33A. As shown in FIGS. 13B, 13C, and 13D, thecentral part 33A-2″ (201A) of the bottom frame 33A-2, is configured sothat it can move independently and separately from the frame 33A.

Therefore, the frame 33A of the present embodiment, as shown in FIGS.13A, 13B, 13C, and 13D, has the first frame 201A, the second frame 200A,the first frame driving unit (not shown), and the second frame drivingunit (not shown). The first frame 201A includes the central part 33A-2″of the bottom frame 33A-2. The second frame 200A is a part other thanthe first frame 201A of the frame 33A. The first frame driving unit andthe second frame driving unit (neither shown) are the units that movethe first frame 201A and the second frame 200A independently. The firstframe driving unit moves the first frame 201A. The second frame drivingunit moves the second frame 200A. Further, the frame 33B has a structuresimilar to the frame 33A. Moreover, the driving system of the framedriving unit should preferably be hydraulic. Thus, the movement of theframes 200A and 201A can easily be controlled. Further, it is preferablethat the frame driving unit be connected to the corresponding centralpart of the first frame 200A or the second frame 201A. The central partsof the frames 200A and 201A are less susceptible to thermal expansion.Thus, by connecting the frame driving unit to the central part which isless susceptible to thermal expansion, the frame driving unit can movethe corresponding frame 200A or 201A in a stable manner, even when theframe 200A or 201A is thermally expanded.

Further, the frame 33A of this present embodiment, as shown in FIGS.13B, 13C, and 13D, has a square shape surrounding the split mold block32A. The first frame 201A includes the lower edge of this square. Also,the second frame 200A includes the upper edge as well as the left andright edges of the square merged together. The first frame 201A and thesecond frame 200A are separate and can be moved independently.Therefore, first, as shown in FIG. 13C, the second frame 200A can bemoved by the second frame driving unit (not shown) and this second frame200A can be brought into contact with the thermoplastic resin sheet P(not shown). After that, as shown in FIG. 13D, the first frame 201A canbe moved by the first frame driving unit (not shown) and this firstframe 201A can be brought into contact with the thermoplastic resinsheet P (not shown). As a result, mounting of the correspondingthermoplastic resin sheet P on the first frame 201A, while thethermoplastic resin sheet P is being suspended along the second frame200A, can be prevented. Thus, resin accumulation at the uppermost end ofthe central part 33A-2″ in the bottom frame 33A-2 can be prevented.Also, the thermoplastic resin sheet P can be suspended down along theU-shaped portion (the second frame 200A). Thus, it is easy to obtainresistance when hanging the thermoplastic resin sheet P downward. Thisallows the draw-down of the thermoplastic resin sheet P to becontrolled.

For example, when the frame 33A with four sides integrally formed isused, there are chances of the central part 33A-2″ of the bottom frame33A-2 being mounted with the lower end of the thermoplastic resin sheetP, when the thermoplastic resin sheet P is suspended along thecorresponding frame 33A. Thus, in the molding apparatus 1 of the presentembodiment, as shown in FIGS. 13C and 13D, only the second frame 200A ismoved and brought into contact with the thermoplastic resin sheet P.After the lower end of the thermoplastic resin sheet P passes throughthe position of the bottom frame 33A-2, the first frame 201A is movedand brought into contact with the thermoplastic resin sheet P. Thisprevents the mounting of the part of resin from the thermoplastic resinsheet P on the central part 33A-2″ of the bottom frame 33A-2. Thus,mounting of the corresponding thermoplastic resin sheet P on the firstframe 201A can be prevented while suspending the thermoplastic resinsheet P along the second frame 200A. Thus, the resin accumulation at theuppermost end of the central part 33A-2″ of the bottom frame 33A-2 canbe prevented. Also, the thermoplastic resin sheet P can be suspendeddown along the U-shaped portion (second frame 200A). Thus, it is easy toobtain resistance when hanging the thermoplastic resin sheet P downward.This allows the draw-down of the thermoplastic resin sheet P to becontrolled.

Also, the frame 33A, as shown in FIG. 13A, has a suction part 34 on thecontact surface 100 to make contact with the thermoplastic resin sheetP. The suction part 34 is a part used to suck air. The thermoplasticresin sheet P is adsorbed onto the frame 33A by the suction of thesuction part 34. Due to this, the thermoplastic resin sheet P isattached firmly to the frame 33A. Further, the suction part 34 can bemolded to have different shapes (for example circular, elliptical, andpolygonal). It is desirable to mold the suction part 34 in a grooveshape (linear shape), as shown in FIG. 13A. For example, when thesuction part 34 is molded in a porous state (point-like), thethermoplastic resin sheet P is only partly adsorbed onto the contactsurface 100. Thus, along the thermoplastic resin sheet P, the partswhich are not adsorbed by the suction part 34, may float from thecontact surface 100. The thermoplastic resin sheet P can be adsorbedonto the contact surface 100 in a groove shape by molding the suctionpart 34 in a groove shape (linear shape). Thus, along the thermoplasticresin sheet P, it becomes harder for parts not adsorbed by the suctionpart 34 to float from the contact surface 100.

<Configuration Example of the Suction Part 34>

Next, the configuration example of the suction part 34 is explained,with reference to FIGS. 14A, 14B, 14C, and 15. FIG. 14A illustrates theexample of the upper surface configuration of the suction part 34. FIGS.14B and 14C show the cross section of the configuration example of thesuction part 34. FIG. 15 illustrates the configuration example of a lidmember 344 configuring the suction part 34.

Further, the frame 33A and the frame 33B shown in FIG. 12 have the samestructure. Thus, as shown in FIGS. 14B and 14C, these frames may berepresented as frame 33 below.

The suction part 34 of the present embodiment, as shown in FIG. 14A, isprovided on the contact surface 100 of the frame 33. As shown in FIG.14B, the frame 33 includes a first recess 341, a second recess 342, ahole 343 and the lid member 344. The first recess 341 is a part that isrecessed inwardly of the contact surface 100. The second recess 342 is apart that is further recessed inwardly of the lower surface of the firstrecess 341. The hole 343 is an opening formed in part of the bottomsurface of the second recess 342. The lid member 344 is arranged on thefirst recess 341.

The lid member 344 has the shape shown in FIG. 15. The lid member 344 isfitted on the first recess 341. The lid member 344 is fixed onto thebottom surface of the second recess 342 by a bonding member 345 such asscrews. The lid member 344 of the present embodiment, as shown in FIG.15, includes a recess 346 that is recessed inwardly of the partcorresponding to the hole 343. FIG. 14B illustrates an example of thecross section configuration of the suction part 34 at the position(position A1-A2) where the recess 346 is set. FIG. 14C illustrates anexample of the cross section configuration of the suction part 34 at theposition (position B1-B2) where the recess 346 is not set. As shown inFIG. 14B, in the positions where the recess 346 is set, a space isformed between the bottom surface of the first recess 341 and the lidmember 344. On the other hand, as shown in FIG. 14C, in the positionswhere the recess 346 is not set, a space is not formed between thebottom surface of the first recess 341 and the lid member 344. In thisposition, the bottom surface of the first recess 341 and the lid member344 come into contact.

In the suction part 34 of the present embodiment, as shown in FIG. 14B,a groove shaped gap 101 (refer to FIG. 14A) is provided between the sidewall of the first recess 341 and the side wall of the lid member 344.This gap 101 and the hole 343 communicate with each other through thespace formed by the recess 346. Also, the hole 343 communicates with asuction path 347 which can be decompressed. Thus, the suction part 34can suck the air on the contact surface 100 through the gap 101 and thespace formed by the suction path 347, the hole 343, and the recess 346.Thus, the thermoplastic resin sheet P can be adsorbed onto the contactsurface 100.

Further, the suction part 34 of the present embodiment can wedge thethermoplastic resin sheet P into the gap 101, while adsorbing thethermoplastic resin sheet P onto the contact surface 100. Thus, it ispreferable that the width of the gap 101 be 0.3 mm or more, and morepreferably 0.5 mm or more. Thus, the thermoplastic resin sheet P can bewedged into the gap 101. As a result, the thermoplastic resin sheet Pcan be attached firmly to the contact surface 100.

Also, the suction part 34 of this embodiment, as shown in FIG. 14A, hasthe groove shaped gap 101 in both ends of the lid member 344. However,it is also possible to provide the groove shaped gap 101 at only one endof the lid member 344. In other words, the suction part 34 of thepresent embodiment may have multi-columned groove shaped gaps 101 oronly one column thereof. However, it is preferable that the suction part34 have multi-columned groove shaped gaps 101. Thus, the thermoplasticresin sheet P can easily be attached firmly to the contact surface 100.

<Molding Process Example of the Molding Apparatus 1>

Next, an example of the molding process of a resin molded product usingthe molding apparatus 1 of the present embodiment is explained, withreference to FIGS. 12 and 16 through 20.

First, as shown in FIG. 12, the thermoplastic resin sheet P is extrudedfrom the T-Die 28A (28B). The extruded thermoplastic resin sheet P issuspended between the pair of the split mold block 32A and the splitmold block 32B.

Once the thermoplastic resin sheet P passes the position of a top frame33A-1 (33B-1) in the frame 33A (33B), as shown in FIG. 16, the secondframe 200A (200B) located along the perimeter of the split mold block32A (32B) is moved toward the thermoplastic resin sheet P. This bringsthe second frame 200A (200B) into contact with the thermoplastic resinsheet P. Therefore, the thermoplastic resin sheet P suspends downwardalong the contact surface (side surface geometry) of the second frame200A (200B).

In such a case, the thermoplastic resin sheet P suspends downward alongthe contact surface 100 of the second frame 200A (200B). Due to this,friction occurs between the thermoplastic resin sheet P and the contactsurface 100. Therefore, the self-weight exerted on the thermoplasticresin sheet P is reduced due to friction. This can control draw-down ofthe thermoplastic resin sheet P.

Moreover, once the second frame 200A (200B) comes into contact with thethermoplastic resin sheet P, in order to push the thermoplastic resinsheet P with the second frame 200A (200B), it is preferable to move thesecond frame 200A (200B) forward only by a certain distance. Therefore,the thermoplastic resin sheet P pushed by the second frame 200A (200B)can be suspended downward along the contact surface of the second frame200A (200B).

Once the lower end of the thermoplastic resin sheet P passes through theposition of the bottom frame 33A-2 (33B-2) in the frame 33A (33B), asshown in FIG. 17, the first frame 201A (201B) is moved toward thethermoplastic resin sheet P. Due to this, the first frame 201A (201B)comes into contact with the thermoplastic resin sheet P. This enablesthe thermoplastic resin sheet P to make contact with the contact surface100 along the entire periphery of the frame 33A (33B). Moreover, asshown in FIG. 17, while the first frame 201A (201B) is brought intocontact with the thermoplastic resin sheet P, the back end of the firstframe 201A (201B) is not positioned further ahead than the cavitysurface 116A (116B). Moreover, during this, the first frame 201A (201B)and the split mold block 32A (32B) are overlapped vertically. This canprevent a gap from forming between the first frame 201A (201B) and thesplit mold block 32A (32B).

After the thermoplastic resin sheet P comes into contact with thecontact surface 100 of the entire periphery of the frame 33A (33B), thesuction part 34 provided at the contact surface 100 sucks the air. Dueto this, the thermoplastic resin sheet P is sucked and can be bonded tothe contact surface 100. As a result, a closed space can be formed bythe thermoplastic resin sheet P, the frame 33A (33B), and the cavitysurface 116A (116B).

After the thermoplastic resin sheet P is bonded to the contact surface100 by the suction part 34 and a closed space is formed, the frame 33A(33B) is moved backward. Due to this, the thermoplastic resin sheet Pcomes into contact with pinch-off parts 118A-1 (118B-1) and 118A-2(118B-2). Subsequently, as shown in FIG. 18, a vacuum suction chamber120A (120B) sucks the air in the closed space through a vacuum suctionhole 122A (122B). Thus, the thermoplastic resin sheet P is adsorbed ontothe cavity surface 116A (116B). As a result, the thermoplastic resinsheet P is shaped into the shape according to the cavity surface 116A(116B).

Next, the frame 33A (33B) and the split mold block 32A (32B) are movedforward. Due to this, as shown in FIG. 19, the split mold blocks 32A and32B move toward each other and are closed. As a result, the pinch-offparts 118A-1 (118B-1) and 118A-2 (118B-2) of the split mold block 32A(32B) weld each rim of the thermoplastic resin sheet P. Therefore, aparting line PL is formed at the contact surface of the twothermoplastic resin sheets P. Moreover, a sealed hollow section 151 isformed inside the two thermoplastic resin sheets P.

Next, as shown in FIG. 20, the split mold blocks 32A and 32B are openedby moving the split mold blocks 32A and 32B away from each other. Then,burrs on the external parts of the resin molded product are removed,after ejecting the molded product. This completes the molding of theresin molded product.

<Operation/Effect of the Molding Apparatus 1 in the Present Embodiment>

In this way, in the molding apparatus 1 of the present embodiment, thesuction part 34 provided in the frame 33A (33B) located along theperimeter of the split mold block 32A (32B) sucks the air. This adsorbsand bonds the thermoplastic resin sheet P extruded from the extrudingmachine 12 to the frame 33A (33B). Then, the thermoplastic resin sheet Pthat is facing the cavity surface 116A (116B) of the split mold block32A (32B) is adsorbed by a vacuum, while it is bonded to the frame 33A(33B). Therefore, the thermoplastic resin sheet P is shaped into theshape according to the cavity surface 116A (116B). Subsequently, a resinmolded product is formed by closing the split mold block 32A and thesplit mold block 32B.

In the molding apparatus 1 of the present embodiment, the thermoplasticresin sheet P extruded from the extruding machine 12 is adsorbed andbonded to the frame 33A (33B) by the sucking of air by the suction part34 provided in the frame 33A (33B). This can prevent gaps from formingbetween the frame 33A (33B) and the thermoplastic resin sheet P.Therefore, the thermoplastic resin sheet P can be shaped into the shapeaccording to the surface of the cavity surface 116A (116B).

Moreover, in the molding apparatus 1 of the present embodiment, theframe 33A (33B) that is movable relative to the split mold block 32A(32B) by being positioned in the periphery of the split mold block 32A(32B), is brought into contact with the thermoplastic resin sheet Pextruded from the extruding machine 12. Then, the frame 33A (33B) ismoved such that the thermoplastic resin sheet P suspends downward as itcomes into contact with the frame 33A (33B). Due to this, thethermoplastic resin sheet P extruded from the extruding machine 12suspends downward while coming into contact with the frame 33A (33B).This produces friction between the thermoplastic resin sheet P and theframe 33A (33B). As a result, the self-weight exerted on thethermoplastic resin sheet P is reduced due to this friction. This cancontrol draw-down of the thermoplastic resin sheet P.

Moreover, the frame 33A (33B) of the present embodiment includes thefirst frame 201A (201B) and the second frame 200A (200B). The bottomframe (33A-2 (33B-2) configuring the lower side of the frame 33A (33B)is at least included in the first frame 201A (201B). The top frame 33A-1(33B-1) configuring the upper side of the frame 33A (33B) is at leastincluded in the second frame 200A (200B), which is movable relative tothe first frame 201A (201B). In the molding apparatus 1 of the presentembodiment, the second frame 200A (200B) is moved closer to thethermoplastic resin sheet P than the first frame 201A (201B).Subsequently, the thermoplastic resin sheet P is suspended downwardwhile being in contact with the second frame 200A (200B). When the lowerend of the thermoplastic resin sheet P reaches a point lower than thesecond frame 200A (200B), the first frame 201A (201B) is moved towardthe thermoplastic resin sheet P and brought into contact with thethermoplastic resin sheet P. This can prevent the resin fromaccumulating at the uppermost end of the central part 33A-2″ (33B-2″) ofthe bottom frame 33A-2 (33B-2).

Moreover, in the embodiment mentioned above, a resin molded product isformed using the molding apparatus 1 shown in FIG. 12. However, it isalso possible to form a resin molded product by using the moldingapparatus 1 having the pair of rollers shown in FIG. 21.

In the molding apparatus 1 shown in FIG. 21, the thickness of thethermoplastic resin sheet P is adjusted by passing it between the pairof rollers 30AA and 30AB (30BB and 30BA). This can reduce the occurrenceof the curtain effect. However, the curtain effect may occur even afterpassing through this roller pair. Therefore, it is preferable to use theframe 33A (33B) similar to that in the molding apparatus 1 shown in FIG.12, even when molding the resin molded product using the moldingapparatus 1 shown in FIG. 21. This can help the definite forming of aclosed space by the thermoplastic resin sheet P, the frame 33A (33B) andthe cavity surface 116A (116B). Thus, the vacuum molding can be donestably. Moreover, when molding a resin molded product using the moldingapparatus 1 having the roller pair shown in FIG. 21, it also becomespossible to mold a resin molded product with an average wall thicknessof 1 mm or less.

Moreover, in the above mentioned embodiment, the frame 33A (33B), asshown in FIGS. 13A, 13B, 13C, and 13D, is separated into the secondframe 200A (200B) and the first frame 201A (201B). Both the frames 200A(200B) and 201A (201B) are set such that they can be movedindependently. Also, the suction part 34 is provided on the contactsurface 100 of each of the frames 200A (200B) and 201A (201B). However,the frame 33A (33B) may also be set up as a combined unit. It is alsopossible to provide the suction part 34 on the contact surface 100 ofthe frame 33A (33B) as the combined unit. In such a case, as shown inFIGS. 22A and 22B, it is also possible to continuously shape the grooveshaped gap 101. Moreover, as shown in FIGS. 22C and 22D, it is alsopossible to intermittently shape the groove shaped gap 101.

Moreover, in the above mentioned embodiment, as shown in FIG. 12, thetop frame 33A-1 (33B-1) set at the upper side of the frame 33A (33B) andthe bottom frame 33A-2 (33B-2) set at the lower side of the frame 33A(33B) are located on an identical vertical line. Subsequently, the frame33A (33B) is brought into contact with the thermoplastic resin sheet Pextruded from the extruding machine 12. Due to this, the thermoplasticresin sheet P is suspended downward while coming into contact with theframe 33A (33B).

However, as shown in FIG. 23, the bottom frame 33A-2 (33B-2) configuringthe lower side of the frame 33A (33B) may protrude toward thethermoplastic resin sheet P, more than the top frame 33A-1 (33B-1)configuring the upper side of the frame 33A (33B). In this structure,the thermoplastic resin sheet P extruded from the extruding machine 12comes into contact between the top frame 33A-1 (33B-1) and the bottomframe 33A-2 (33B-2). The contacted thermoplastic resin sheet P suspendsdownward along the contact surface (side surface geometry) 100 of theframe 33A (33B).

In this structure, the thermoplastic resin sheet P suspends downwardalong the contact surface 100 of the frame 33A (33B). Due to this,friction occurs between the thermoplastic resin sheet P and the frame33A (33B). Therefore, the self-weight exerted on the thermoplastic resinsheet P is reduced due to this friction. This can control draw-down ofthe thermoplastic resin sheet P.

Moreover, it is desirable to construct the frame 33A (33B) shown in FIG.23 similar to the frame 33A (33B) shown in FIG. 12, so that the firstframe 201A (201B) and the second frame 200A (200B) can be movedindependently. This can prevent the resin from accumulating at theuppermost end of the central part 33A-2″ of the bottom frame 33A-2.

Third Embodiment

The third embodiment is explained as follows.

<An Overview of the Molding Apparatus 1 of the Third Embodiment>

First, the overview of the molding apparatus 1 of the third embodimentis explained with reference to FIG. 24.

The molding apparatus 1 in the present embodiment includes the extrudingmachine 12 and the clamping machine 10. The extruding machine 12extrudes the molten and mixed thermoplastic resin P in the sheet form.The clamping machine 10 brings the frame 33A (33B), which can moverelative to the split mold block 32A (32B) and is located along theperimeter of the split mold block 32A (32B), into contact with thethermoplastic resin P extruded in the sheet form from the extrudingmachine 12. Next, the clamping machine 10 adsorbs by a vacuum thethermoplastic resin P that faces the cavity surface 116A (116B) of thesplit mold block 32A (32B) to the cavity surface 116A (116B). Therefore,the thermoplastic resin sheet P can be shaped into the shape accordingto the cavity surface 116A (116B). Consequently, a resin molded productis formed by closing the split mold block 32A and the split mold block32B.

The frame 33A (33B) of the molding apparatus 1 in the present embodimentis movable relative to the split mold block 32A (32B). The bottom frame33A-2 (33B-2) configuring the lower side of the frame 33A (33B)protrudes more toward the thermoplastic resin P than the top frame 33A-1(33B-1) configuring the upper side of the frame 33A (33B).

In the molding apparatus 1 of the present embodiment having the abovementioned structure, the thermoplastic resin P extruded in the sheetform from the extruding machine 12 suspends downward along the contactsurface 100 of the frame 33A (33B). Therefore, the frame 33A (33B) cancome into contact with the thermoplastic resin P. As a result, gapsappearing, between the frame 33A (33B) and the thermoplastic resin P canbe prevented. Therefore, the thermoplastic resin P can be shaped intothe shape according to the cavity surface 116A (116B). Below, themolding apparatus 1 of the present embodiment is explained in detailwith reference to the attached drawings.

<A Configuration Example of the Molding Apparatus 1>

First, the configuration example of the molding apparatus 1 in thepresent embodiment is explained with reference to FIG. 24. The moldingapparatus 1 of the present embodiment has a structure similar to that ofthe molding apparatus 1 of the second embodiment shown in FIG. 12,except for the frame 33A (33B). Therefore, the explanations of partshaving the same symbols as FIG. 12 are omitted. Moreover, the operationof the frame 33A on the thermoplastic resin sheet P is the same as thatof the frame 33B. Therefore, in this explanation of the configurationexample of the molding apparatus 1, the structure and operation of theframe 33A are mainly explained. In the contact surface 100 of the frame33A in the present embodiment, as shown in FIGS. 24 and 25B, the bottomframe 33A-2 configuring the lower side of the frame 33A protrudes moretoward the front than the top frame 33A-1 configuring the upper side ofthe frame 33A. As the frame 33A is moved ahead, as shown in FIG. 27, thebottom frame 33A-2 of the frame 33A will be closer to the split moldblock 32B than the suspending position of the thermoplastic resin sheetP. Due to this, the thermoplastic resin sheet P suspended downward fromthe T-Die 28A comes into contact with the frame 33A, and, after contact,suspends downward along the contact surface 100 of the frame 33A. Thisensures that the frame 33A comes into contact with the thermoplasticresin sheet P. Thus, gaps appearing between the frame 33A and thethermoplastic resin sheet P can be prevented. Moreover, thethermoplastic resin sheet P suspends downward along the contact surface100 of the frame 33A. Due to this, friction occurs between thethermoplastic resin sheet P and the frame 33A. Therefore, theself-weight exerted on the thermoplastic resin sheet P is reduced bythis friction. This can control draw-down of the thermoplastic resinsheet P.

Moreover, it is preferable that a position of the frame 33A, where thethermoplastic resin sheet P suspended downward from the T-Die 28A comesinto contact, be lower than the uppermost end of the top frame 33A-1.This is because, when the uppermost end of the top frame 33A-1 comes incontact with the thermoplastic resin sheet P, part of the resin of thethermoplastic resin sheet P is mounted on the uppermost end of the topframe 33A-1, which can cause accumulation of resin at the uppermost endof the top frame 33A-1. Therefore, it is preferable for thethermoplastic resin sheet P to make contact at a point lower than theuppermost end of the top frame 33A-1. Thus, possible resin accumulationcan be avoided.

Moreover, the contacting position of the frame 33A with thethermoplastic resin sheet P should preferably be lower than theuppermost end of the top frame 33A-1, and more preferably higher thanthe uppermost end of the split mold block 32A. In this case, aftercoming into contact with the frame 33A, the thermoplastic resin sheet Psuspends downward along the contact surface 100 of the frame 33A, whichcan form a closed space inside the frame 33A and the cavity surface116A. Moreover, when the contacting position of the frame 33A with thethermoplastic resin sheet P is lower than the uppermost end of the splitmold block 32A, a gap occurs between the lower end of the top frame33A-1 of the frame 33A and the contacting position of the thermoplasticresin sheet P with the frame 33A. Due to this, the closed space cannotbe formed by the thermoplastic resin sheet P, the frame 33A and thecavity surface 116A. In this case, the pinch-off part 118A-1 at theupper end comes into contact with the lateral surface of thethermoplastic resin sheet P. Then, a closed space is formed by thethermoplastic resin sheet P, the pinch-off part 118A-1 at the upper end,the cavity surface 116A, and the frame 33A. Moreover, as the method ofbringing the pinch-off part 118A-1 at the upper end into contact withthe lateral surface of the thermoplastic resin sheet P, there are amethod in which the pinch-off part 118A-1 at the upper end is made tocontact the lateral surface of the thermoplastic resin sheet P by movingthe split mold block 32A forward, and a method in which the lateralsurface of the thermoplastic resin sheet P is made to contact thepinch-off part 118A-1 at the upper end by moving the frame 33A, which isin contact with the thermoplastic resin sheet P, backward. Due to this,the closed space can be formed by the thermoplastic resin sheet P, thepinch-off part 118A-1 at the upper end, the cavity surface 116A, and theframe 33A.

Moreover, the contact surface 100 between the top frame 33A-1 and thebottom frame 33A-2 of the frame 33A shown in FIG. 25B has a planarshape. However, the contact surface 100 between the top frame 33A-1 andthe bottom frame 33A-2 need not necessarily be a planar shape, as longas the shape allows the downward suspending of the thermoplastic resinsheet P along the contact surface 100 of the frame 33A. For example, asshown in FIGS. 26A and 26B, a part of this contact surface 100 can alsobe a curved surface. Moreover, as shown in FIG. 25B, when the contactsurface 100 has a planar shape, it is preferable to set the inclineangle (θ) of the contact surface 100 in the frame 33A within the rangeof 2 to 40 degrees, and more preferably within the range of 5 to 15degrees. If the incline angle (θ) of the contact surface 100 is toosmall, the contact surface 100 will have to be elongated. Otherwise, theprobability of the thermoplastic resin sheet P coming into contact withthe uppermost end of the top frame 33A-1 of the frame 33A will be high.Moreover, if the incline angle (θ) of the contact surface 100 is toolame, the protruding amount of the bottom frame 33A-2 will be large.Therefore, the probability of the thermoplastic resin sheets P cominginto contact with each other will be high. Thus, the incline angle (θ)of the contact surface 100 should preferably be set within the specificrange (2 to 40 degrees) corresponding to the length of the contactsurface 100. Moreover, the incline angle (θ) of the contact surface 100should more preferably be set within the specific range (2 to 40 degree)taking into consideration the frictional force that occurs between thethermoplastic resin sheet P and the frame 33A.

Moreover, in order to prevent resin from accumulating in the uppermostend of the top frame 33A-1 of the frame 33A, as shown in FIG. 26C, it ispossible to provide a notch 101 at the uppermost end of the top frame33A-1. This can reduce the probability of the thermoplastic resin sheetP contacting the uppermost end of the top frame 33A-1 of the frame 33A.Moreover, the shape of the notch 101 is not limited to a specific shape.As long as contact of the thermoplastic resin sheet P with the uppermostend of the top frame 33A-1 is prevented, any shape is acceptable for thenotch 101.

Moreover, in the present embodiment, the thermoplastic resin sheet Psuspends downward along the contact surface 100 of the frame 33A.Therefore, resin may be accumulated even in the uppermost end of thebottom frame 33A-2 of the frame 33A. Therefore, as shown in FIG. 26D,only the both ends (parts of the bottom frame 33A-2 configuring thecontact surface 100 of the frame 33A) 33A-2′ of the bottom frame 33A-2may be more protruded forward than the top frame 33A-1. In such a case,the central part 33A-2″ other than both the ends 33A-2′ of the bottomframe 33A-2 will be depressed to an inner side. Therefore, thethermoplastic resin sheet P along the contact surface 100 of the frame33A will come into contact with both the ends 33A-2′ of the bottom frame33A-2 when it is suspended downward, but will not come into contact withthe center part 33A-2″. This prevents the accumulation of resin in thebottom frame 33A-2. However, in this case, a gap appears between thethermoplastic resin sheet P and the central part 33A-2″ of the bottomframe 33A-2. Thus, it becomes necessary to bring the pinch-off part118A-2 of the lower end to come in contact with the lateral surface ofthe thermoplastic resin sheet P.

Moreover, as another method to avoid the accumulation of resin, thecentral part 33A-2″ of the bottom frame 33A-2 may be separated from theframe 33A. In such a case, preferably, moving the central part 33A-2″independently from the other parts should be possible. In thisstructure, the central part 33A-2″ is moved forward after thethermoplastic resin sheet P suspends downward along the contact surface100 of the frame 33A and passes the bottom frame 33A-2. Thus, it is thenpossible to bring the central part 33A-2″ in contact with the lateralsurface of the thermoplastic resin sheet P.

Moreover, a suction hole may also be provided in the frame 33A to adsorbthe thermoplastic resin sheet P. In this structure, it is possible toadsorb the thermoplastic resin sheet P onto the frame 33A by sucking theair through the suction hole. This allows the thermoplastic resin sheetP suspended along the contact surface 100 of the frame 33A to beadsorbed onto the frame 33A (33B). Moreover, the timing to start thesucking of the thermoplastic resin sheet P from the suction hole shouldpreferably be after the thermoplastic resin sheet P is suspendeddownward from the bottom frame 33A-2 of the frame 33A. Consequently,after the thermoplastic resin sheet P is suspended downward along thecontact surface 100 of the frame 33A, the thermoplastic resin sheet Pcan be adsorbed onto the contact surface 100 of the frame 33A (33B).

<An Example of the Molding Process in the Molding Apparatus 1>

Next, the molding process of the resin molded product by the moldingapparatus 1 of the present embodiment is explained with reference toFIGS. 24, and 27 through 30.

First, as shown in FIG. 24, the thermoplastic resin sheet P is extrudedfrom the T-Die 28A (28B). The extruded thermoplastic resin sheet P issuspended between the pair of split mold block 32A and the split moldblock 32B.

Moreover, as shown in FIG. 27, the frame 33A (33B) located along theperimeter of the split mold block 32A (32B) is moved forward toward thethermoplastic resin sheet P. This brings the frame 33A (33B) intocontact with the thermoplastic resin sheet P.

In the frame 33A (33B) of the present embodiment, the bottom frame 33A-2(33B-2) is protruded more toward the front than the top frame 33A-1(33B-1). Therefore, the thermoplastic resin sheet P suspended from theT-Die 28A (28B) can be brought into contact with the frame 33A (33B),and the thermoplastic resin sheet P brought into contact with the frame33A (33B) can be suspended downward along the contact surface 100 of theframe 33A (33B). As a result, as shown in FIG. 27, a closed space can beformed by the thermoplastic resin sheet P, the frame 33A (33B) and thecavity surface 116A (116B). Also, the thermoplastic resin sheet Psuspends downward along the contact surface 100 of the frame 33A. Thus,friction occurs between the thermoplastic resin sheet P and the frame33A. Therefore, the self-weight exerted on the thermoplastic resin sheetP is reduced due to this friction. This can control draw-down of thethermoplastic resin sheet P.

When the thermoplastic resin sheet P brought into contact with the frame33A (33B) is suspended downward along the contact surface 100 of theframe 33A (33B) and reaches a point lower than the lowermost end of thebottom frame 33A-2 (33B-2) of the frame 33A (33B), the frame 33A (33B)is moved backward. Therefore, the thermoplastic resin sheet P can bebrought into contact with the pinch-off parts 118, 118A-1 (118B-1), and118A-2 (118B-2). Subsequently, as shown in FIG. 28, the air within theclosed space is sucked by the vacuum suction chamber 120A (120B) throughthe suction hole 122A (122B). This allows the thermoplastic resin sheetP to be adsorbed onto the cavity surface 116A (116B). Consequently, thethermoplastic resin sheet P is shaped into the shape according to thecavity surface 116A (116B). Moreover, while sucking the air within theclosed space, preferably, the thermoplastic resin sheet P should beshaped into the shape according to the cavity surface 116A (116B) afterthe thermoplastic resin sheet P is inflated toward the cavity surface116A (116B). Therefore, the thermoplastic resin sheet P can effectivelybe shaped into the shape according to the cavity surface 116A (116B).

Next, only the split mold block 32A (32B) is moved forward while theframe 33A (33B) is moved backward. Therefore, as shown in FIG. 29, thesplit mold blocks 32A and 32B move closer to each other and are closed.Consequently, the pinch-off parts 118, 118A-1 (118B-1), and 118A-2(118B-2) of the split mold block 32A (32B) weld the rims of thethermoplastic resin sheet P together. Therefore, a parting line PL isformed at the joining surface of the two thermoplastic resin sheets P.Moreover, a sealed hollow section 151 is formed inside the twothermoplastic resin sheets P.

Next, as shown in FIG. 30, the split mold blocks 32A and 32B are openedby moving the split mold blocks 32A and 32B away from each other. Then,the resin molded product is ejected, and the burrs on the externalsurface of the resin molded product are removed. This completes themolding of the resin molded product.

<Operation/Effect of the Molding Apparatus 1 in the Present Embodiment>

In this way, the frame 33A (33B) is provided in the molding apparatus 1of the present embodiment. The frame 33A (33B) is located along theperimeter of the split mold block 32A (32B) and is movable relative tothe split mold block 32A (32B). The bottom frame 33A-2 (33B-2)configuring the lower part of the frame 33A (33B) is protruded moretoward the thermoplastic resin sheet P than the top frame 33A-1 (33B-1)configuring the upper part of the frame 33A (338).

Therefore, the thermoplastic resin sheet P extruded from the extrudingmachine 12 comes into contact between the top frame 33A-1 (33B-1) andthe bottom frame 33A-2 (33B-2). Subsequently, the thermoplastic resinsheet P suspends downward along the contact surface 100 of the frame 33A(33B). This ensures that the frame 33A (33B) comes into contact with thethermoplastic resin sheet P. This prevents gaps from appearing betweenthe frame 33A (33B) and the thermoplastic resin sheet P. Therefore, thethermoplastic resin sheet P can be shaped into the shape according tothe cavity surface 116A (116B).

Moreover, in the above mentioned embodiment, the resin molded product isformed using the molding apparatus 1 shown in FIG. 24. However, it isalso possible to form the resin molded product using the moldingapparatus 1 having a pair of rollers shown in FIG. 31.

In the molding apparatus 1 shown in FIG. 31, the wall thickness of thethermoplastic resin sheet P is adjusted by passing it through a pair ofrollers 30AA and 30AB (30BB and 30BA). Therefore, the occurrence of thecurtain effect can be reduced, and a thermoplastic resin sheet P with athin wall can be formed. However, the curtain effect may occur evenafter passing through these roller pairs. Therefore, even when moldingthe resin molded product using the molding apparatus 1 shown in FIG. 31,it is desirable to use the frame 33A (33B) similar to that of themolding apparatus 1 shown in FIG. 24. Therefore, a closed space candefinitely be formed by the thermoplastic resin sheet P, the frame 33A(33B) and the cavity surface 116A (116B). Thus, the vacuum molding canbe done stably. Moreover, when molding the resin molded product usingthe molding apparatus 1 having a pair of rollers, as shown in FIG. 31,it is also possible to mold a resin molded product having an averagewall thickness of 1 mm or less.

Also, in the embodiment mentioned above, after the thermoplastic resinsheet P is extruded from the T-Die 28A (28B), as shown in FIG. 27, theframe 33A (33B) located along the perimeter of the split mold block 32A(32B) is brought into contact with the thermoplastic resin sheet P.Then, the thermoplastic resin sheet P is suspended downward along thecontact surface 100 of the frame 33A (33B). However, the thermoplasticresin sheet P may be extruded from the T-Die 28A (28B) after the frame33A (33B) is moved in advance. Even in such a case, it is possible tobring the thermoplastic resin sheet P into contact with the frame 33A(33B) and then to suspend it downward along the contact surface 100 ofthe frame 33A (33B). In other words, as long as it is possible tosuspend the thermoplastic resin sheet P downward along the contactsurface 100 of the frame 33A (33B), there are no specific restrictionsfor the timing of moving the frame 33A (33B), it is possible to move theframe 33A (33B) at any timing.

It is noted that the above-described embodiments are preferredembodiments of the present invention. The scope of the present inventionis not limited to the above-described embodiments. The present inventioncan be implemented in various modified modes without departing from thegist of the present invention.

What is claimed is:
 1. A molding apparatus that adsorbs thermoplasticresin extruded in a sheet form from an extruding machine, onto a cavityof a mold, and shapes the thermoplastic resin into a shape according tothe cavity, comprising a frame that is positioned on a periphery of themold and is movable relative to the mold, wherein a suction part forsucking the thermoplastic resin is provided in a contact surface of theframe to contact the thermoplastic resin, and the suction part isprovided in a linear shape along with a longitudinal direction of theframe positioned on the periphery of the mold.
 2. The molding apparatusaccording to claim 1, wherein the suction part comprises: a first recessrecessed inwardly of the contact surface; a second recess recessedfurther inwardly of a bottom surface of the first recess; a hole formedby opening a part of a bottom surface of the second recess; a lid memberpositioned in the first recess, a gap linearly formed between a sidewall of the first recess and a side wall of the lid member, andcommunicates with the hole, and the hole communicates with a suctionpath which can be decompressed.
 3. The molding apparatus according toclaim 2, wherein the lid member includes a recess recessed toward thecontact surface at the part corresponding to the hole, and the holecommunicates with the gap through a space formed by the recess providedin the lid member.
 4. The molding apparatus according to claim 3,wherein the recess is provided in a position where a space is formedbetween the bottom surface of the first recess and the lid member, andthe hole communicates with the gap through the space.
 5. The moldingapparatus according to claim 3, wherein the recess is not provided in aposition of the lid member where the space is not formed between thebottom surface of the first recess and the lid member, and the bottomsurface of the first recess contacts the lid member.
 6. A molding methodthat uses the molding apparatus according to claim 1, comprising: adriving step in which a contact surface of a frame positioned on aperiphery of a mold and movable relative to the mold is brought intocontact with thermoplastic resin extruded from an extruding machine in asheet form and the frame is moved so that the thermoplastic resin issuspended downward while coming in contact with the contact surface, asucking step in which, after contacting of the thermoplastic resin withthe contact surface on a whole perimeter of the frame, air is sucked infrom a suction part provided in the contact surface in a linear shapealong with a longitudinal direction of the frame so as to adsorb thethermoplastic resin in a linear shape to the contact surface, and tobond the thermoplastic resin to the frame, and a shaping step in whichthe thermoplastic resin wedged onto the contact surface of the frame andfacing a cavity of the mold is adsorbed onto the cavity, to shape thethermoplastic resin into a shape according to the cavity.